The major hypothesis to be tested by this proposal is that the effects seen on myelin and oligodendrocytes in AIDS brain are the result of indirect toxicity by products and/or actions of HIV-infected macrophages or T lymphocytes. This is important to determine because 90% of AIDS patients show CNS involvement at autopsy and 65'v suffer from clinically progressive cognitive, motor, and behavioral abnormalities. White matter shows the most distinctive abnormalities with perivascular foci of inflammation and demyelination in spinal cord and brain. Also evident are modular syncitia of macrophages, astrogliosisofloss or abnormality of oligodendrocytesp the myelin producing cells. Specifically, normal blood T cells or macrohages (MO) will be infected JJ2 vitro with HIV. Alternatively, AIDS patients' blood or cerebrospinal fluid (CSF) T cells or MO will be isolated. The production by these celll of lytic/inhibitory cytokines will the measured in vitro. T cells may produce lymphotoxin (LT) or transforming growth factor beta (TGF beta); MO may procuce tumor necrosis factor (TNF) or interleukin I (7.Ll). All 4 cytokines have also been shown to be cytcstatic or cytotoxic for malignant as well as normal cells. The ability of these products of HIV-infected cells to affect growth or metabolism of oligodendrocytes will be examined in vitro using recombinant proteins as standard controls; normal primary human and rat glial cultures as well as cell lines will be used as targets in standard cytctoxicity assays. Direct MO antibody dependent cellular cytotoxicity assays can be performed with infected cells as effectors. Specificity wlll be determined by inhibition with cytokine specific antibodies. The effect of HIV-Infected cells or their supernatants to interfere with cell growth will be determined by examining their inhibition of oligodendroglial cell response to known specific growth factors such as interleukin-2, epidermal growth factor, fibroblast growth factor, and insulin-like growth factor-I. Because primary rat clial cells differentiate in culture, we can also monitor the ability of HIV-infected cells or cell products to prevent myelin associated protein production by Northern blot analysis of MRNA levels for myelin basic protein, myelin associated glycoprotein, and proteolipid protein